I'm taking off the Shimano ultegra groupset supplied with my new scott cr1. I've got the cranks off but I need to get the press fit BB cups out (of an 86.5mm plain carbon shell) so I can fit campag ones. Is there a method I can use to push them out gradually without putting any stress on the frame? I did try using a plastic ended hammer and a sturdy piece of plastic rod to try and tap the cups out but they have not budged a mm. I know there is a tool used to drift them out but that involves using a hammer too.